More than 600 active volcanoes on Earth Kilauea in Hawaii erupts continuously. Iceland is a country...
-
Upload
isabelle-brunger -
Category
Documents
-
view
217 -
download
0
Transcript of More than 600 active volcanoes on Earth Kilauea in Hawaii erupts continuously. Iceland is a country...
VOLCANOES
Most Active Volcanoes
More than 600 active volcanoes on Earth Kilauea in Hawaii erupts continuously. Iceland is a country that is made entirely
from volcanoes.
Effects of Eruptions Volcanic ash and debris can
Kill crops and forests Kill people Destroy habitats
Sulfuric acid from volcanic gases mixes with water vapor to create acid rain. Gases and ash particles can block
sunlight from entering Earth’s atmosphere lowering the overall temperature of the planet. Watch this pyroclastic flow from Mt.
Unzen, Japan: http://www.youtube.com/watch?v=Cvjwt9nnwXY
Human and Environmental Impacts
Soufriere Hills, Montserrat 1995 Volcanologists
knew it was about to erupt.
Some folks refused to leave.
Pyroclastic flows wiped out cities and towns in its path, killing 20 people who ignored the evacuation order.
Volcanoes Plates moving apart—divergent boundaries
Iceland’s volcanoes emerged from seafloor spreading
Eyjafjallajökull eruption 2010 http://www.youtube.com/watch?v=tGPD_0SCDp4
Plates moving together—convergent boundaries Soufriere Hills, Montserrat 2007
http://www.youtube.com/watch?v=8sPyyHY57H4
Hot Spot Volcanoes Hawaii’s Kilauea is the most active volcano in
the world. http://www.youtube.com/watch?v=488BkTUsMa4
How the Hawaiian Islands Formed
Over a period of about 5 million years, the Pacific plate has moved over a hot spot where mantle material is particularly hot and blasts through Earth’s crust like a torch.
The lava that leaks out at the hot spot built up and formed a volcanic island.
As the plate moves over the hot spot, the magma punches through a new spot in the crust, forming new islands.
Volcanoes that are no longer over a hot spot become dormant or extinct.
The volcanic islands that are quiet begin to erode by the ocean waves.
Hawaiian Islands
Older
Newer
Kilauea
Kilauea at Night
Kilauea Lava Tube
Subduction Zone Volcanoes(convergent plate boundaries)
An oceanic plates subducting under another oceanic plate will create an island arc.
An oceanic plate subducting beneath a continental plate will create coastal volcanoes.
Subduction Zone Volcanoes(convergent plate boundaries)
VOLCANIC NECK
Shiprock, New Mexico
DIKES NEAR SHIPROCK
Devil’s Tower, Wyoming, a Volcanic Neck
Volcanic Dike near Devil’s Tower
Volcanic Dike near Devil’s Tower
Another View of the Volcanic Dikes
Another View of the Volcanic Dikes
Volcanic Sill
Granitic Batholiths Exposed!
Yosemite Park,California
Formation of a Caldera
Colorado’s Volcanic Past
The Fish Canyon eruption in southwestern Colorado about 28 million years ago erupted more than 5,000 km3 (3,107 miles3) of magma from the La Garita caldera. That is enough magma to bury the entire state of California to a depth of nearly 39 feet.
Colorado has at least nineteen calderas including one of the world’s largest, the La Garita Caldera. It is so large (22 by 47 miles) that for a long time it was hard for geologists to realize that they were mapping in a giant caldera.
More on La Garita
The scale of La Garita volcanism was far beyond anything known in human history. The resulting deposit, known as the Fish Canyon Tuff, has a volume of approximately 5,000 cubic kilometers (1,200 cu mi), enough material to fill Lake Michigan (in comparison, the May 18, 1980 eruption of Mt. St. Helens was only 1.2 cubic kilometers (0.3 cu mi) in volume).
La Garita Caldera
Crater Lake, Oregon Crater Lake formed around 5,677 (±
150) BC when Mount Mazama exploded.
Crater Lake is the deepest lake in the Western Hemisphere and the third deepest in the world.
Its deepest point has been measured at 1,949 feet.
Crater Lake and Wizard Island
Geologic Map of Mt. Mazama